Replacement endless vehicle tracks

ABSTRACT

A replacement endless drive track for use on a heavy duty tracked vehicle such as a bulldozer or tank includes a reinforced polymeric drive belt, two parallel sets of closely spaced rail blocks adjacent the drive belt, a plurality of drive pins extending between opposing ones of the rail blocks, and supporting members adjoining the drive belt and the rail blocks. The rail blocks are substantially Z-shaped, such that a forward portion of one rail block is offset and overlaps the rearward portion of a directly adjacent rail block. The rail blocks, drive pins and drive treads may be comprised of a polymeric material which is harder than the polymeric material of the drive belt. The drive pins may alternatively be disposed at a lateral end of the supporting members to accommodate a tracked vehicle with peripherally disposed drive sprockets. In addition, the frame of the tracked vehicle may be adapted to provide for attachment of widened rollers which roll directly on the track for smoother and quieter travel. In an alternative manner, a conventional endless track may be modified to accommodate the widened rollers by fixing a plurality of supporting pads to the grousers of the endless track, the widened rollers riding directly on the supporting pads.

This is a Continuation-in-Part of Application No. 07/926,521, filed Aug.10, 1992 now U.S. Pat. No. 5,368,376 which in turn is aContinuation-in-Part of application Ser. No. 07/749,896 filed Aug. 26,1991 (now abandoned).

BACKGROUND OF THE INVENTION

The present invention relates to a replacement endless track for a heavyduty tracked vehicle. Endless tracks are used on heavy duty vehiclessuch as tractors, bulldozers, and tanks. As shown in FIG. 1, such avehicle includes an endless track drive system 2 made up of a closedloop endless track 3 in conjunction with the necessary sprocketed drivewheel 4 and any necessary supporting wheels, such as opposite end wheel5 and idler wheels or rollers 6. The endless track is installed so as topass around the wheels 4, 5 and 6. Of course, the tracked vehicle isfurther equipped with the necessary power source and controls to powerthe endless track drive system and thereby propel the vehicle overvarying terrain as desired.

As seen in FIG. 2, one conventional endless track 3 consists of twoparallel rails 7 each comprised of a plurality of rail blocks 7' linkedtogether and supporting a plurality of metal grousers 8. Metal drivepins 9 between opposing rail blocks are engaged by the drive wheelsprocket to propel the vehicle. Drive pins 9 are typically driven intoand retained by press fittings 10 in the rail blocks. Replaceableprotective metal bushings 9' may be provided around drive pins 9 toprotect the drive pins from wear, and a lubricant may be injectedbetween drive pins 9 and bushings 9' from reservoirs in drive pins 9 toreduce friction. Examples of this type of track are disclosed, forexample, in U.S. Pat. Nos. 2,823,082; 3,734,577; 3,955,855; 4,359,248;and 4,530,546. See also Catepillar's Sealed and Lubricated Trackbrochure.

As seen in FIG. 2A, another conventional track 3A consists of aplurality of central guide members 7A and a plurality of metal grousers8A. The grousers 8A are held together by a plurality of drive units 9Adisposed on the peripheral edges of the track 3A. The drive units 9A areengaged by drive wheel sprockets to propel the vehicle. Each drive unit9A includes a pair of laterally extending pins 10A and a connectingmember 12A. Laterally extending pins 10A of adjacent grousers are fittedinto one of connecting members 12A.

The above-referenced conventional tracks have the disadvantages of beingnoisy and vibration prone, not sufficiently durable and/or not usable onroad surfaces. This is because of the conventional configurations anduse of metal parts. Accordingly, substantial efforts have been made toconstruct quieter, smoother operating and more durable tracks fortracked vehicles of rubber, polyurethane or other polymeric materials.See, e.g., Applicants' own U.S. Pat. Nos. 4,093,318; 4,569,561;4,616,883; Re. 33,324; 4,844,560; 4,861,120; 4,884,852; 4,906,054;5,005,921; 5,005,922; 5,020,865; and 5,040,282 (fully incorporatedherein by reference). See also, e.g., U.S. Pat. No. 4,904,030 and PCTPublication No. WO 85/2824. However, these tracks and tracks like themsuffer from the disadvantage that direct replacement of theabove-described conventional metal tracks is not possible. In otherwords, some modification of the conventional tracked vehicle isnecessary in order to accommodate these polymeric tracks. Moreover,further improvements in durability are still needed.

Thus, there remains a need for replacement endless vehicle tracks whichovercome the foregoing problems.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been developed to overcome theforegoing shortcomings of previous endless vehicle tracks.

It is therefore an object of the present invention to provide areplacement endless vehicle track which can be substituted for aconventional track without modification (or without significantmodification) of the tracked vehicle.

It is yet another object of the present invention to provide areplacement endless vehicle track which substantially reduces noise,vibration and wear, which has a substantially longer useful life, andwhich renders the tracked vehicle usable on paved roadways in additionto other terrains.

It is yet another object of the present invention to provide areplacement endless vehicle track which can be easily and quicklyinstalled on existing tracked vehicles.

Thus, in accordance with one aspect of the present invention, theshortcomings of existing endless vehicle tracks are overcome by anendless vehicle track comprising a polymeric drive belt having a centrallongitudinal axis and first and second surfaces; a plurality of closelyspaced first rail blocks adjacent the first surface of the drive beltalong a line parallel to the central longitudinal axis; a plurality ofclosely spaced second rail blocks adjacent the first surface of thedrive belt along a line parallel to but across the central longitudinalaxis from the plurality of first polymeric rail blocks; a plurality ofdrive pins respectively extending between opposing ones of said firstand second rail blocks; and a plurality of drive treads adjacent thesecond surface of the drive belt.

In accordance with another aspect of the present invention, a pluralityof supporting members are provided, substantially perpendicular to thecentral longitudinal axis. At least one reinforcement member may bedisposed through the supporting members and within the drive beltsubstantially parallel to the central longitudinal axis, the first andsecond rail blocks being secured to the supporting members, and thedrive treads being formed on the supporting members. Each supportingmember is alternatively a one-piece construction or includes detachabledrive belt and tread portions.

In accordance with yet another aspect of the present invention, each ofthe rail blocks includes a forward portion and a rearward portion, theforward portion of one rail block being offset from and overlapping therearward portion of a directly adjacent rail block.

In accordance with still another aspect of the present invention, thedrive treads may be comprised of a polymeric material which is harderthan a polymeric material of the drive belt. The rail blocks and drivepins may also be comprised of a polymeric material which is harder thanthe polymeric material of the drive belt.

In accordance with still further aspects of the present invention, therail blocks are comprised of metal. The drive pins may include metalouter protective bushings, and the bushings and rail blocks may becoated with a polymeric material. A lubricant may be provided betweenthe drive pins and the bushings. A sealing member and/or an O-ringlocated inwardly of the sealing member may be provided to seal in thelubricant.

In accordance with yet a further aspect of the present invention, thedrive belt either may be cable reinforced or polyester reinforced. Morespecifically, the drive belt may be reinforced with polyester belts.

In accordance with yet further aspects of the present invention, thedrive belt is either integrally molded with the drive treads or isbolted to the drive treads; the drive treads lie under and verticallysupport each of the rail blocks or longitudinally alternating ones ofthe rail blocks; and a longitudinal width of the drive treads isapproximately equal to a longitudinal width of portions of the railblocks abutting the drive belt.

In accordance with yet further aspects of the present invention, thesupporting members may be metal; abutting ends of the endless vehicletrack may be joined with a master link; and the master link may comprisea pair of rail blocks and a drive pin between the rail blocks.

In accordance with yet another aspect of the present invention, anendless track drive system for a tracked vehicle includes the foregoingendless vehicle track in conjunction with a sprocket for engaging withthe drive pins and driving the tracked vehicle. The endless track drivesystem may also include at least one supplemental sprocket for engagingwith the supporting members, a supplemental drive wheel for frictionallyengaging with the tops of the rail blocks and/or a supplemental drivewheel for frictionally engaging with the first surface of the drivebelt, to thereby further drive the tracked vehicle. In addition, theendless track drive system may include an apparatus for adapting a frameof the tracked vehicle to provide for attachment of widened rollerswhich are adapted to ride directly on the first surface of the drivebelt.

In accordance with still another aspect of the present invention, anendless vehicle track includes a polymeric drive belt having a centrallongitudinal axis and first and second surfaces; a plurality ofsupporting members substantially perpendicular to the centrallongitudinal axis and connected to the drive belt, a lateral end portionof each of the supporting members including a drive pin with an outerprotective bushing for engagement with a drive sprocket, and a lubricantprovided between the drive pin and the outer protective bushing. Thelateral end portion includes a cut out portion and a detachable end cap,and the drive pin is press fitted into apertures in the cut out portionand the end cap such that the bushing is free to rotate within the cutout portion and is engageable with the drive sprocket. At least oneguide member is attached to each of the supporting members at centrallocations thereon.

In accordance with another aspect of the present invention, an endlessvehicle track includes at least one metal grouser and a pair of parallelrails, each of the rails including a plurality of rail blocks. The metalgrouser is fixed to ones of the rail blocks. The endless vehicle trackfurther includes at least one roller for guiding the track and at leastone supporting pad fixed to the metal grouser, the roller riding on thesupporting pad. The supporting pad can be formed of polyurethane or someother polymeric material, and can be fixed to the grouser by molding orwith bolts. At opposite ends of the pad are a tapered slot and a tabmember, respectively. In a related embodiment, a supporting pad isadapted to be fixed to a grouser of a conventional endless track. Thesupporting pad supports a roller that guides the track.

These and other aspects and advantages of the present invention aredescribed in or appear from the following detailed description of thepreferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments are described with reference to the drawingsin which:

FIG. 1 is a perspective view of a bulldozer equipped with a conventionalsprocket driven rail-type endless vehicle track;

FIG. 2 is a partial enlarged view of the conventional rail-type endlessvehicle track of FIG. 1;

FIG. 2A is a partial enlarged view of an alternative conventionalendless vehicle track;

FIG. 3 is a perspective view of the replacement endless vehicle track inaccordance with the present invention;

FIG. 4 is a partial enlarged view of the replacement endless vehicletrack of the present invention;

FIGS. 5A-5C depict various tread configurations which may be used on theendless vehicle track of FIG. 3;

FIGS. 6A-6E are alternative lateral cross sections of the endlessvehicle track of the present invention, taken along the line VI--VI ofFIG. 4;

FIGS. 7A and 7B are alternative longitudinal cross sections of theendless vehicle track of the present invention taken along the lineVII--VII of FIG. 4;

FIG. 8 is a partial plan view of the endless vehicle track of thepresent invention;

FIG. 9 is a master link for use in conjunction with the endless vehicletrack of the present invention;

FIGS. 10A-10C depict various supplemental drive configurations for usein conjunction with the present invention;

FIG. 11 depicts an alternative construction for the present invention;

FIG. 12 is a perspective view of a portion of an alternative embodimentof the present invention;

FIG. 13 is a lateral cross section of the FIG. 12 embodiment of thepresent invention;

FIG. 14 is a partial plan view of the endless vehicle track of the FIG.12 embodiment of the present invention;

FIG. 15 is a perspective view of portions of yet another embodiment ofthe present invention;

FIG. 16 is an elevation view of the FIG. 15 embodiment showing widenedrollers;

FIG. 17 is a perspective view of a tracked vehicle frame adapted withextenders to accommodate the widened rollers of FIG. 16;

FIG. 18 is a perspective view of one of the extenders of FIG. 17;

FIG. 19 is a perspective view of portions of still another embodiment ofthe present invention;

FIG. 20 is a perspective view of the drive pin and bushing arrangementof the FIG. 19 embodiment of the present invention;

FIG. 21 is a perspective view of a portion of the FIG. 12 embodimentshowing auxiliary supporting members;

FIG. 22 is a perspective view of yet another embodiment of the presentinvention;

FIG. 23 is a side elevational view of the tab and slot arrangement ofthe FIG. 22 embodiment; and

FIG. 24 is a perspective view of a modification of the FIG. 22embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 3 and 4 depict an endless vehicle track 11 in accordance with thepresent invention. This track is to be used as a direct replacement forthe conventional rail-type track depicted in FIGS. 1 and 2. Accordingly,a pair of such tracks are to be installed on a tracked vehicle, such asthe bulldozer depicted in FIG. 1.

Each endless vehicle track 11, when installed, comprises a continuous,closed loop structure 12 constructed of a polymeric material. Thepolymeric structure is preferably molded, but may be constructed inother ways. The polymeric structure may be formed of any polymericmaterial which will provide a durable, sprocket-driven track withlimited operational noise; examples are rubber, polyurethane or otherplastics. One specific example is B-839 polyurethane manufactured byUniroyal Chemical Company.

Polymeric structure 12 includes a polymeric drive belt 13, preferablyreinforced with reinforcement members 14. Drive belt reinforcementmembers 14 are preferably KEVLAR belts, but also may be cables, cords orbelts made of steel, other metals, nylon, polyester, or other highstrength, light weight materials. Drive belt 13 has a centrallongitudinal axis X, and first and second surfaces 15 and 16.

A first set of closely spaced rail blocks 17 are fixed to the firstsurface of the drive belt 13 along a line parallel to the centrallongitudinal axis X. A second set of closely spaced rail blocks 18 arefixed to the first surface of the drive belt 13 along a line parallel tobut across central longitudinal axis X from the first set of railblocks. A plurality of drive pins 19 respectively extend betweenopposing ones of the first and second rail blocks.

A plurality of supporting members or braces 20 preferably respectivelyadjoin the drive belt and the rail blocks 17, 18. The supporting membersmay fully extend from the rail blocks to the lateral edge of the track,or they may be truncated short of the lateral edge of the track. Theymay have a constant height, or may be tapered as shown. They may havesharp or rounded edges and ends. As described more fully below, each ofthe rail blocks and/or supporting members may include a locking memberfor positively locking the rail blocks 17, 18 and/or the supportingmembers 20 into fixed positions with respect to the drive belt.

A plurality of drive treads 21 are fixed to the second surface 16 of thedrive belt 13. For optimum support, drive treads should be provideddirectly under each of the rail blocks 17, 18 and their supportingmembers 20. However, drive treads may be provided under less than all ofthe rail blocks and supporting members such as, for example, underlongitudinally alternating pairs of the rail blocks and supportingmembers. FIGS. 5A-5C depict three possible tread configurations. In thedesign of FIG. 5A (also shown in FIG. 4), each tread consists of threeequal sized tread portions 21. In this design, the central tread portionsupports a laterally opposed pair of rail blocks 17, 18, whereas theouter tread portions support the corresponding supporting members 20. Inthe design of FIG. 5B, each tread 21' extends substantially the fulllateral width of the endless vehicle track. In the design of FIG. 5C,every other tread 21' extends substantially the full lateral width ofthe track, whereas intervening treads 21" extend only under thecorresponding rail block and supporting member, with a spacethere-between corresponding to the space between opposed rail blocks 17,18. Other possible tread designs will be apparent to persons skilled inthe art.

In order for the endless vehicle track 11 to be a direct replacement forthe conventional rail-type track depicted in FIGS. 1 and 2, drive pins19 must be spaced the same distance apart as drive pins 9 of theconventional track. In the disclosed embodiment, rail blocks 17, 18 aresized and disposed on drive belt 13 such that two adjacent rail blocks17 or 18 have the same longitudinal length as one of the rail blocks 7'of the conventional track. Accordingly, inclusion of drive pins 19between every other pair of rail blocks 17, 18 ensures that the spacingbetween drive pins 19 is equal to the spacing between drive pins 9 ofthe conventional track.

As can be seen in FIGS. 6-8, rail blocks 17, 18 and drive pins 19 mayinclude reinforcing structure made of steel, other metals, high strengthpolyurethane, or similar high strength material. For example, railblocks 17, 18 may be reinforced with 1/4-inch steel plates 31 welded toa 3/4-inch steel rod 32 extending through a 1/2-inch coating ofpolymeric material comprising drive pin 19. T-shaped locking members 33may also be provided which extend into drive belt 13 and positively lockthe respective rail blocks 17, 18 into fixed positions with respect tothe drive belt 13. T-shaped members 33 preferably extend beneath railblocks 17, 18 and supporting members 20, but may extend only beneathrail blocks 17, 18. T-shaped members 33 may be formed as extensions ofmetal plates 31 as shown in FIG. 7A, or as extensions of polyurethanerail blocks 17, 18 as shown in FIG. 7B. In either case, drive belt 13may be directly molded around the T-shaped members as further shown inFIG. 7A, or metal or polyurethane female receptacles 33' may beincorporated into drive belt 13. In the latter case, rail blocks 17, 18and/or supporting members 20 may be slid into receptacles 33' andretained in place with appropriate end caps and fasteners, similar tothose described below with reference to FIG. 9.

Although the drive pins 19 are shown in FIG. 6A as being constructed ofa polymeric coated steel rod, it will be appreciated that the drive pinsmay be constructed in any way sufficient to accommodate the forcesimposed by the sprocket and to ensure against undue wear. Thus, as shownin FIG. 6B, the drive pins 19 of FIG. 6A may include a metal (e.g.,steel) or high strength polymeric (e.g., polyurethane) or polymericcoated metal bushing 19'. Bushing 19' may be stationary or may rotate tofurther reduce wear. If stationary, bushing 19' may be extended intorail blocks 17, 18 and welded to plates 31 within the rail blocks. Thedrive pins also may be constructed of steel without a polymeric coatingas shown as element 319 in FIG. 6E.

As shown in FIGS. 6C and 6D, the drive pins may alternatively comprisemetal pins 119, 219 which extend through holes in rail blocks 17, 18 andreinforcing plates 31, are retained within press fittings 22, and areprotected against wear by polymeric or metal (or polymeric coated metal)bushings 119', 219'. The bushings preferably rotate to further reducewear, and washers 41 are preferably provided to reduce friction betweenthe bushings and the rail blocks. The spaces between the drive pins andbushings may be unlubricated as shown in FIG. 6D, or a lubricant 60 maybe provided between the drive pins and bushings from reservoirs 61 inthe drive pins as shown in FIG. 6C. In that event, relatively highcompression lubricant seals 63 (of rubber or other sealing material)should be provided in the ends of the bushings. O-rings 63' (of rubberor other sealing material) may also be provided inside seals 63 toprovide auxiliary sealing in the event of failure of seals 63.Reservoirs 61 may be permanently sealed so as to require no replenishingof lubricant (see, e.g., FIG. 13), or reservoirs 61 may be periodicallyrefilled by removal of a cap 62 or through a lubricating fitting (notshown) in the cap or end of the drive pin.

As is evident from FIG. 8, each of rail blocks 17, 18 is substantiallyZ-shaped such that a forward portion of one rail block (18' as shown) isoffset from and overlaps a rearward portion of a directly adjacent railblock (18" as shown). This permits the adjacent rail blocks to move withrespect to one another as the endless vehicle track flexes, while at thesame time permitting rims of the drive sprocket or drive wheel tosmoothly ride upon the tops of rail blocks 17, 18. This configuration ofthe rail blocks also prevents undue accumulation of dirt and debrisbetween the drive pins and the sprocket.

Although the entire endless vehicle track may be constructed of a singlepolymeric material, in order to simultaneously optimize the integrityand durability of the structural members and the flexibility of thedrive belt it is preferable to construct the rail blocks, drive pins(including any bushings) and supporting members of a polymeric materialwhich is harder than the polymeric material of the drive belt. Forsimilar reasons, the drive treads may also be made of a polymericmaterial which is harder than the polymeric material of the drive belt.Thus, for example, the rail blocks, drive pins, supporting members anddrive treads may be made of PET-75-D polyurethane manufactured by AirProducts Company, whereas the drive belt may be made of B-839polyurethane manufactured by Uniroyal Chemical Company.

In the manufacture of the endless vehicle track of the presentinvention, the drive belt and drive treads may be integrally molded withthe rail blocks, drive pins and supporting members, whether the variouscomponents are made of a single polymeric material or differentpolymeric materials. Alternatively, the drive belt and drive treads maybe bolted to the rail blocks and/or supporting members as shown in FIG.11. In the latter case, threaded steel plates 70 may be installed in therail blocks and/or supporting members to receive and retain the bolts71.

The endless vehicle track may be molded without reinforcing structure31, 32, 33 and/or 33', or by ensuring that the reinforcing structure issuspended in the mold along with reinforcement members 14 prior toinjection of the polymeric material. If the various components of theendless vehicle track are all made of a single polymeric material, thetrack may be formed in a single molding step. If the various componentsof the track are made of different polymeric materials, the track may beformed in single or multiple molding steps. In the former case, forexample, specified quantities of the different materials may besimultaneously injected into different parts of the mold. In the lattercase, for example, the rail blocks, drive pins, supporting members anddrive treads may be first integrally molded of a relatively hardpolyurethane material with the drive treads connected to the rail blocksand supporting members with lugs 40 as shown in FIG. 6A, while leavingspace for subsequent injection of the polymeric material for the drivebelt. In a subsequent step, the drive belt is then molded of arelatively soft polyurethane material which integrates with or bonds tothe harder polyurethane material of the rail blocks, drive pins,supporting members and drive treads. Since connecting lugs 40 extendonly between the rail blocks/supporting members and the drive treads,drive belt 13 is free to fully flex between adjacent railblocks/supporting members.

The endless vehicle track of the present invention may be molded in aclosed loop for installation on the tracked vehicle. Alternatively, tomake installation of the track easier and quicker, the endless track mayhave two abutting ends joined together by a master link such asdisclosed in FIG. 9. In this case, ends of reinforcing belts 14 arefolded back during the molding process to leave reinforcing belt loops14' extending from opposite ends of the endless vehicle track. Theextending loops at each end are then looped around a wedge-shaped rod 50which includes recessed portions 51 for receiving the belt loops. Thetwo ends of the endless vehicle track are then brought into abutment,and the rods 50 with the belt loops 14' are slid into an H-shaped link52 which includes wedge-shaped recesses 53 which are shaped and sized toreceive rods 50 and belt loops 14', preferably in a snug fit. An end cap54 is provided at at least one end of link 52 to retain rods 50 in link52; the other end of link 52 may also include an end cap or may beintegrally closed during manufacture. Each end cap 54 is fastened tolink 52 with screws, bolts, or other conventional fasteners (not shown).Rail blocks 17, 18, drive pin 19 and/or supporting members 20 may bedisposed on master link 52 in positions respectively corresponding tothe positions of like elements on the endless vehicle track.

As an alternative to the master link shown in FIG. 9, the endlessvehicle track of the present invention may be utilized in conjunctionwith a master link or joint assembly as disclosed in Applicants' otherU.S. patents identified above, particularly U.S. Pat. Nos. 4,844,560 and5,020,865. The grooved or recessed rods disclosed in those patents andin the embodiment of FIG. 9 herein could be comprised of a central rod(e.g., 1/2 inch O.D.) with washers (e.g., 1 inch O.D.) spaced apartthereon to thereby effectively create the grooves or recessed portionsbetween the spaced washers. Of course, any such alternative master linkmay also include rail blocks, drive pin and/or supporting members asdescribed above.

Once installed on a tracked vehicle, the endless vehicle track of thepresent invention is positively driven by engagement between theexisting sprocket 4 and the drive pins or their bushings. However, it ispossible to provide supplemental or alternative driving power for thetracked vehicle. For example, one or more supplemental sprockets 72 maybe included for engaging with the supporting members 20 as shown in FIG.10A. Additionally, one or more pneumatic drive wheels 73, 74 may beprovided for frictionally engaging with the tops of the rail blocksand/or with the first surface of the drive belt as shown in FIGS. 10Band 10C. Other possibilities will be apparent to those skilled in theart on the basis of the foregoing disclosure.

In an alternative embodiment, with reference to FIGS. 12-14, a pair ofmetal rail blocks 417, 418, by way of example 1/2 to 1 inch wide steel,are welded or otherwise fastened to a metal (e.g., steel) supportingmember 420. The rail blocks may be polymeric coated as shown in FIG. 13,or may be utilized without any polymeric coating. The supporting member420 includes a plurality of slots 420' adapted to receive reinforcementmembers 414 prior to molding of the drive belt. Similar to the earlierembodiments described above, a drive pin 419 is press fitted directlyinto apertures 422 in rail blocks 417, 418, and a bushing 419' (metal,polymeric or polymeric coated metal) is provided over the drive pin forengaging with the sprocketed drive wheel of the tracked vehicle.

Apertures 422 of rail blocks 417,418 are preferably offset from acentral vertical axis of the rail blocks. By means of the offsetapertures, two parallel sets of overlapping rail blocks can be achievedwith the manufacture of a single rail block type (by simply reversingthe orientation of opposing rail blocks), while minimizing the necessarysize of overlapping portions and consequent material waste duringmanufacture.

During manufacture, each individual assemblage of rail blocks,supporting member, drive pin and bushing is coated at the bottom with apolymeric material (preferably a relatively hard polyurethane) with thereinforcement member receiving slots 420' exposed to thereby form atread member 421, as depicted in FIG. 12. A plurality of the railblock/supporting member/drive pin/bushing assemblages are then placedside by side, with appropriate reinforcement members 414 through therespective slots 420' of the respective supporting members, and thedrive belt 413 is molded around the reinforcement members 414 and theupper portions of the supporting members 420 as best depicted in FIG.13. As described above with reference to earlier embodiments, the drivebelt is preferably formed of a polymeric material which is relativelysofter than the material utilized to form treads 421 or any materialutilized to coat rail blocks 417, 418 and bushings 419'. Similar to theearlier described embodiments, the vehicle track can be formed in asingle molding step or multiple molding steps. Likewise, the endlessvehicle track of this embodiment may be molded in a closed loop, oralternatively may have two abutting ends joined together by a masterlink as previously described.

In a modified version of this alternative embodiment, with reference toFIGS. 15 and 16, supporting members 520 include a lower (tread) portion520" and two upper (drive belt) portions 520"' (each with reinforcementmember receiving slots 520'), which are adapted to be bolted together asbest shown in FIG. 16. As can be seen from the drawings, a tread 521 ismolded around lower portion 520"' of supporting member 520. Similarly,drive belt 513 is molded around upper portions 520"' of supportingmember 520. Drive belt 513 is then bolted to respective tread members521 to form the endless vehicle track. In this modified version of thealternative embodiment, rail blocks 517, 518 are welded or otherwisefastened to lower portion 520" of supporting member 520.

In the embodiments of FIGS. 12-16, the drive belt is preferablycomprised of two parallel portions as shown. The upper surface (i.e.,rail block side) of the drive belt is smooth, since it does not includesurface mounted supporting members 20 of the first embodiment. The uppersurface of the drive belt in these embodiments may be flat or taperedoutwardly from the rail blocks. The taper may be a partial taper asdepicted in FIG. 16, or the drive belt may be continuously tapered fromthe respective rail block to the outer lateral edge of the drive track.In the case of a partial taper, a reverse partial taper may be providedat the outer lateral end of each drive belt portion so that the drivebelt portions can be removed, flipped end for end, and reversed in theevent of excessive wear on the tapered surfaces. It is also preferablethat the horizontal axis of the drive belt be aligned with orsubstantially aligned with the horizontal axes of the various drivepins, to avoid undesirable stretching or compressing of the drive beltduring use.

In the embodiments of FIGS. 12-16, the entire endless vehicle track maybe constructed of a single polymeric material or multiple polymericmaterials as described above with reference to earlier embodiments. Ineither event, it is preferable to maintain a tread hardness of 90-95durometers (A scale), and an overall track hardness in the range of70-95 durometers (A scale). This may be accomplished through the use ofthe previously identified polyurethane materials. Alternatively, thedrive belt, for example, may be made of B-602 polyurethane manufacturedby Uniroyal Chemical Company, or the entire vehicle track may be made ofPCA 422 polyurethane manufactured by Polyurethane Specialties Co., Inc.

In conventional rail-type track vehicles, the metal rollers (FIG. 1,reference numeral 6) typically ride atop the rail blocks, resulting inan additional source of undesirable noise and excessive wear. To reducenoise, the metal rollers may be replaced with standard width, polymericor polymeric coated rollers requiring no modification of the vehicleframe. In order to provide for an even smoother, quieter and moredurable operation, the standard metal rollers 6 may alternatively bereplaced with metal, polymeric or polymeric coated metal rollers 106(see FIG. 16) Which ride on the upper surface of the drive belt insteadof atop the rail blocks. In order to accommodate these widened rollers,roller mounting extenders 600 (FIGS. 17, 18) are bolted or otherwisefastened to portions of the vehicle frame which have beencorrespondingly cut out to accommodate the extenders, and the widenedrollers are then bolted or otherwise fastened to flanges 601 of theextenders. If it is later desired to use the standard width rollers(metal, polymeric or polymeric coated metal) with the modified frame,adaptors 602 may be removably fastened to extenders 600, as shown inFIG. 18. Of course, rollers 106 can be flat or tapered, to match theupper surface of the corresponding drive belt with which they are to beutilized.

To avoid stretching of the drive belt by the widened rollers betweensupporting members, polymeric auxiliary supporting members 800 may beincluded between the supporting members as shown in FIG. 21 (preferablyunder or substantially under the rollers). As shown, two auxiliarysupporting members protrude from each side of a drive tread, and areoffset from overlapping auxiliary supporting members protruding from anadjacent drive tread, so as to provide both freedom of movement andauxiliary support for the widened rollers. The auxiliary supportingmembers are preferably made of a relatively hard polymeric materialintegrally molded with the drive tread, and may be steel reinforced. Theauxiliary supporting members preferably have flat upper surfacesdirectly adjacent the lower surface (drive tread side) of the drivebelt, and are tapered downwardly to the drive tread as shown.

With reference to FIGS. 19 and 20, the present invention may be evenfurther modified for use on track vehicles, such as tanks, whichincorporate drive sprockets which engage with lateral end portions ofthe drive track. This embodiment may be constructed similarly to theembodiments of FIGS. 12-16, except that the lower portions 720" ofsupporting members 720 are widened to accommodate drive pins 719 andbushings 719' at their lateral end portions. More particularly, thelateral ends of the lower portion 720" of each supporting member 720include cut out portions 750. Drive pins 719 are press fitted intoapertures in lower portion 720" of each supporting member 720 and capmembers 751, the latter being bolted or otherwise detachably fastened tolower portion 720" such that bushing 719' is free to rotate (ifpreferred) and is further engageable with the sprocketed drive wheel.Metal, polymeric or polymeric coated metal guide members 752 arefastened to central portions of supporting members 720 to maintainlateral positioning of the endless vehicle track.

In yet another alternative embodiment, referring to FIGS. 22 and 23, aconventional endless track can be modified to accommodate the widened,metal, polymeric or polymeric coated metal rollers 106 illustrated inFIG. 16. As described in connection with FIG. 2, the endless trackincludes two parallel rails 7 each comprised of a plurality of railblocks 7' linked together and supporting a plurality of metal grousers8. Metal drive pins 9 between opposing rail blocks are engaged by thedrive wheel sprocket to propel the vehicle. Drive pins 9 are driven intoand retained by press fittings 10 in the rail blocks. Replaceableprotective metal bushings 9' may be provided around drive pins 9 toprotect the drive pins from wear, and a lubricant may be injectedbetween drive pins 9 and bushings 9' from reservoirs in drive pins 9 toreduce friction. Attached to each of the metal grousers 8 are a pair ofsupporting pads 20' made of a polymeric material such as polyurethane.Pads 20' are fixed to grousers 8 by any suitable means, such as bymolding or by bolts received in threaded holes in the grousers or innuts on the other side of the grousers. Pads 20' may be flat or taperedoutwardly from the rail blocks as described above with reference to thedrive belt of FIGS. 12-16. Rollers 106 are widened and ride on thesupporting pads 20'. This pad and roller arrangement enables aconventional endless track to be modified for smoother, quieter and moredurable operation.

At one end of each of supporting pads 20' is a tab 20'A. The tab 20'A isadapted to be received in (engaged with) a corresponding slot 20'B of anadjacent pad 20'. As shown in FIG. 23, tab 20'A and slot 20'B arecorrespondingly tapered with respect to each other, preferably such thatslot 20'B tapers from a top surface to a bottom surface toward the tab20'A of an adjacent pad wherein the widest part of the tapered portionfaces the rollers 106, and tab 20'A tapers from a top surface to abottom surface of the pad toward the slot 20'B of the same pad. Thetapered slot provides sufficient space for pivotal movement of the tab,thereby avoiding contact with the adjacent pad when the endless track isturning around the drive wheel or opposite end wheel.

Referring to FIG. 24, grouser 8 may be coated with or formed completelyof a polymeric material such as polyurethane. A reinforcing member 25formed of a strong material, such as steel, is disposed within thegrouser 8. Supporting pads 20' are fixed to grouser 8 in a mannersimilar to that described above in connection with FIG. 22. In addition,supporting pads 20' may be formed integral with grouser 8.

Thus, while only certain embodiments of the invention have beenspecifically described herein, it will be apparent that numerousmodifications may be made thereto without departing from the spirit andscope of the invention.

What is claimed is:
 1. An endless track for an endless track vehicle,said endless track comprising:at least one metal grouser; a pair ofparallel rails, each of said rails comprising a plurality of railblocks, said metal grouser being fixed to ones of said rail blocks; andat least one roller supporting pad fixed to said metal grouser, saidsupporting pad engaging with an adjacent supporting pad.
 2. The endlesstrack of claim 1, wherein said supporting pad is molded to said grouser.3. The endless track of claim 1, wherein said supporting pad is fixed tosaid grouser with bolts.
 4. The endless track of claim 1, wherein saidsupporting pad is made of a polymeric material.
 5. The endless track ofclaim 1, wherein said supporting pad comprises a tab at a first end anda slot at a second end, said tab protruding in a direction parallel tosaid rails and shaped to fit inside a corresponding slot of saidadjacent supporting pad.
 6. The endless track of claim 5, wherein saidslot tapers from a top surface to a bottom surface in a direction fromthe first end of said supporting pad toward the second end of saidsupporting pad, respectively, and said tab correspondingly tapers from atop surface to a bottom surface from the first end of said supportingpad toward the second end of said supporting pad, respectively.
 7. Asupporting pad adapted to be fixed to a grouser of an endless track ofan endless track vehicle and to support a roller that guides the track,said supporting pad comprising:a front end and a rear end; means forfixing said supporting pad to said grouser; and means for engaging anadjacent supporting pad such that a portion of said pad extends from oneof said front end and said rear end and past the other of a front endand a rear end of said adjacent supporting pad and within said adjacentsupporting pad.
 8. The supporting pad of claim 7, wherein said fixingmeans comprises supporting said pad being molded member to said grouser.9. The supporting pad of claim 7, wherein said fixing means comprisesbolts.
 10. The supporting pad of claim 7, wherein said supporting pad ismade of a polymeric material.
 11. The supporting pad of claim 7, whereinsaid supporting pad comprises a tab at a first end and a slot at asecond end, said tab protruding in a first direction and shaped to fitinside a corresponding slot of said adjacent supporting pad.
 12. Thesupporting pad of claim 11, wherein said slot tapers from a top surfaceto a bottom surface in a direction from the first end of said supportingpad toward the second end of said supporting pad, respectively, and saidtab correspondingly tapers from a top surface to a bottom surface fromthe first end of said supporting pad toward the second end of saidsupporting pad, respectively.
 13. An endless track for an endless trackvehicle, said endless track comprising:a plurality of grousers; a pairof parallel rails, each of said rails comprising a plurality of railblocks, said grousers being linked to one another by said rail blocks;and a pair of roller supporting pads fixed to each of said grousers. 14.The endless track of claim 13, wherein said supporting pads are fixed tosaid grousers by bolts.
 15. The endless track of claim 13, wherein saidgrousers are formed of a polymeric material and include a reinforcingmember.
 16. The endless track of claim 15, wherein said supporting padsare integral with said grousers.
 17. The endless track of claim 15,wherein said reinforcing member is a steel bar disposed within saidpolymeric grousers.
 18. An endless track for an endless track vehicle,said endless track comprising:at least one metal grouser; a pair ofparallel rails, each of said rails comprising a plurality of railblocks, said metal grouser being fixed to ones of said rail blocks; andat least one roller supporting pad fixed to said metal grouser, saidsupporting pad, together with an adjacent supporting pad, providing asubstantially continuous pad surface, wherein said supporting padcomprises a front end and a rear end, and wherein a portion of said padextends from one of said front end and said rear end and past the otherof a front end and a rear end of said adjacent supporting pad and withinsaid adjacent supporting pad.
 19. An endless track drive system for atracked vehicle, said system comprising:at least one metal grouser; apair of parallel rails, each of said rails comprising a plurality ofrail blocks, said metal grouser being fixed to ones of said rail blocks;at least one roller for guiding the track; and at least one supportingpad fixed to said metal grouser, said roller riding on said supportingpad, said supporting pad engaging with an adjacent supporting pad. 20.An endless track drive system for a tracked vehicle, said systemcomprising:at least one metal grouser; a pair of parallel rails, each ofsaid rails comprising a plurality of rail blocks, said metal grouserbeing fixed to ones of said rail blocks; at least one roller for guidingthe track; and at least one supporting pad fixed to said metal grouser,said roller riding on said supporting pad, said supporting pad, togetherwith an adjacent supporting pad, providing a substantially continuouspad surface, wherein said supporting pad comprises a front end and arear end, and wherein a portion of said pad extends from one of saidfront end and said rear end and past the other of a front end and a rearend of said adjacent supporting pad and within said adjacent supportingpad.
 21. An endless track drive system for a tracked vehicle, saidsystem comprising:a plurality of grousers; a pair of parallel rails,each of said rails comprising a plurality of rail blocks, said grousersbeing linked to one another by said rail blocks; a plurality of rollersfor guiding the track; and a pair of supporting pads fixed to each ofsaid grousers, said rollers riding on ones of said supporting pads, saidsupporting pads, together with adjacent supporting pads, providing asubstantially continuous pad surface.